The easiest way is to put it in a glass of water. If the egg sinks, it is very fresh. If it stays submerged , but with the wide end up, it is older, but still perfectly edible. If your egg floats, it should be tossed.

http://www.food52.com/hotline...Oddly enough, this question from yesterday covers issues regarding this. The ultimate test: crack the egg into a bowl (by itself, not with your other ingredients), check visually and by smell. Bad eggs smell terrible. Really fresh eggs have a raised yolk and the white mostly sticks together. As eggs get older, the yolk doesn't sit as high, and the white seeps away from the edges -- but still good for many uses.